Static assert for illegal construction, fix manual
RefCountedObject.h calls assert(); therefore it should #include <cassert> as LuaBridge.h does
fix puzzling errors in addProperty: previously, for example, a property of

int getter()

would cause

new(malloc(sizeof(fptr))) int(fptr)

which doesnt make any sense to me at all? changed code to resemble luabridge 1.0.2, and it fixes it.

oddly, luabridge 1.0.2's properties would crash for me, something having to do with the types of the lightuserdata getting unpacked wrongly in the function caller. glad luabridge 2.0 fixed it, once i fixed it.
Use *integer() Lua routines for integral Stack conversions
Pass by const reference for primitive & container types

Added specializations of Stack<T> to support passing primitive
types and container types by const reference in addition to
passing them by value without triggering asserts at run time.